Broke things by removing old assets that were still init'd but never used. Fixing that.
Fixed broken item spawn
Adding some error handling to bad map setup with detailed logging
Spawn areas read in tiles in a layer instead.

* not yet generally handled
* only one area at a time
* spawnArea doesn't actually get setup yet
* spawnableItems has been moved to layer properties, but game doesn't know that yet.
Multiple areas can be setup and have knowledge of their respective items.

* no spawning actually happens yet
Initial spawning works.

* Can stand some cleanup/refactoring
* turn on timer again
Refactored, turned on timer

* BUG why is the timer action firing twice and spawning 2 at a time?
Fixed double-spawn bug.
Merge pull request #238 from icbat/mapImprovements

Map improvements